Process of enhanced solvency induction



July 28, 1942. J. E. HARVEY, JR 2,291,315l

' PROCESS 0F ENHANCED S O.T.|VENCY INDUCTION Filed March 14, 1941 #wwwFfLSLfQf/f Patented July 28, 1942 PROCESS OF ENHANCED SOLVENCY INDUCTIONJ acquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half toSouthern Wood Preserving Company, East Point, Ga., a corporation ofGeorgia Application March 14, 1941, lSerial No. 383,465

. Claims.

This invention relates to the enhanced production of solvents.

More specifically, the present invention relates to the enhancedinduction of solvency in tars of aromatic content and fractions thereof,including pitches and stripped tars.

This application is a continuation in part of my application Sr. No.352,654, led August 14, 1940, for Process of enhanced solvencyinduction, copending herewith, as to all matter common to the twoapplications.

An object of the present invention is the enhanced induction of solvencyin tars of aromatic content and fractions thereof by the step-Wiseaction of hydrogen, as more fully explained in the following.

A further object of the invention is the enhanced induction of solvencyby catalytic means with added provision of maintaining catalysis ofoptimum conditions.

Further objects of the present invention will become apparent from thefollowing disclosures.

Starting materials of the present process are tars of aromatic contentderived from coal, wood, petroleum, gas and/or gases and fractionsthereof derived therefrom. Especially attractive as a starting materialis tar or fractions derived from coal, as for instance coke oven tar,gas house tar, or low temperature tar. These tars derived from coal, andmore especially coke oven tar, are characterized by the presence of highmolecular complexes that are so susceptible to thermal degradation thatthe solvents of the present invention cannot be provided by a singleaction of hydrogen but must be produced in step-wise manner ashereinafter described. According to the process of the present inventionit is further possible, by recycling operations, to convertsubstantially the entirety of the starting materials remaining liquidinto solvents of enhanced value.

It has been found that the induction of solvency, as hereinafterdescribed, is maintained at optimum rate when catalyzed by a sulfidecatalyst, provided that said catalyst be maintained atleast to a degreesubstantially in sulphide form. An important part of the presentinvention consists of maintaining at least a portion of a sulphidecatalyst in sulde form whereby to'enhance production of solvents ascompared to produc` tion of solvents that flow from a catalyzed reactionwherein the entirety or part of the sulfide catalyst is changed toanother form. (f

The following examples will serve to illustrate the general principleupon which the practice of the present invention is based, 'as well asthe process of the present invention.

The invention will be understood from the following description ofillustrative steps comprising various methods of securing the objects ofthe invention, when read in connection with the accompanying drawingvwherein the'gure I a diagrammatic sketch of an apparatus for carryingout a form ofthe process of the invention and wherein the nature of thestep carried out in each chamber and the contents thereof are indicatedby legend.

Example 1.-A high residue creosote having substantially 48% boiling at355 C. and substantially 2% coke residue is charged to a high pressureautoclave with addition of onek half/ of one percent sulphur based oncre'osote, and subjected to the action of hydrogen at 200 atmosphere`spressure and a temperature of 400 C.; catalyst molybdenum sulfide; timeof reaction, one hour. At the end of the hour period the beneficiatedcreosote is withdrawn from the autoclave and will be found to havereduced coke residue, specific gravity and viscosity. The beneciatedmaterial is then distilled to an upper limit of 250 C. to provide thedistillate as an intermediate starting material. 'I'he intermediatestarting material is then subjectedA in the autoclave to the furtheraction of hydrogen wherein temperature is 475 C. and the pressure 200atmospheres; catalyst, molybdenum and chromium sulfide; one eighth ofone percent sulphur is added to the intermediate starting material priorto being charged to the autoclave Processing of the intermediatestarting material is continued until sample withdrawn show that therehas been induced an increment of low ,boiling fractions in excess offractional increment in the high boiling range and the beneficiatedmaterial has a solvency in excess of its intermediate parent material.

The catalysts aforenamed were repeatedly used in recurring cycles ofhydrogen action and maintained substantially their initial activityotherA thandecrease expected through normal aging.

Some starting materials may contain sufficient sulfur to maintain thecatalyst in substantial sulfide form, while others require the additionof sulphur thereto. It is difficult to define the sulphur contentnecessary, inasmuch as thestarting materials vary in sulphur content. Asa general rule it can be said that the maintenance of a hydrogen sulfidepartial pressure of in the order of one atmosphere will suice formaintaining the ble of generating hydrogen sulfide may be added to thestarting material.

Viewed broadly, the present invention provides .inasmuch as enhancedreaction flows from the maintenance of said hydrogen sulfide atmosphere'in only the first cycle.

Example 2.-'-A coal tar, specific gravity 1.1641, coke .residue inexcess of 8% and boiling predominantly above 190 C. is passed through ahigh pressure` reaction vessel while simultaneously flowing hydrogen andhydrogen sulfide therewith at a temperature of 410 C. and 350atmospheres pressure; hydrogen sulfide partial pressure one atmosphere;catalyst tin sulfide; time of reaction, 75 minutes and the flow ofhydrogen 12,000,

cubic feet per barrel feed. The beneficiated tar is distilled to anupper limit of 260 C. to provide the distillate as an intermediatestarting material. The intermediate 'starting material is then passedthrough a high-pressure reaction rvesselV while` .simultaneously flowinghydrogen therel with;' catalyst molybdenum sulfide; flow of hydrogen6,000 cubic feet per barrel of feed stock; time of contact 2 minutes.The beneficiated material will be found to have a solvency. in excess ofits intermediate starting material and will be characterized byincrement of low boiling fractions in excess -of fractional, incrementVin the high boiling range.

Example 3.--A tar fraction of aromatic content, initial boiling pointsubstantially 220 C. and having substantially 50% residue above 355 C.is subjected to the action of hydrogen while contacting a cobalt sulfidecatalyst. Temperature is maintained at 410 C. and a pressure at 400atmospheres; time of contact, one hour; hydrogen sulfide partialpressure one and one-half atmospheres. The beneficiated material will befound to have a lowered coke residue, specific gravity, `and viscosity,and condensation of boiling points toward the lower end. Thebeneficiated material is distilled to an upper limit of 320 C. with thedistillate serving as the intermediate starting material. Theintermediate starting material is subjected to the action of hydrogenand hydrogen sulfide while contacting f a 'sulfide catalyst at atemperature of 465 C.

pheres pressure; catalyst vanadium sulfide; the

time of Contact is one and one-half hours; hydrogen sulde partialpressure two atmospheres. The beneflciated pitch is again subjected toan identical cycle of hydrogenation. The twice beneficiated pitch isdistilled to an upper limit of 210 C.` to provide a distillate as anintermediate starting material for solvents of the present invention.The distillate is then subjected to the action of hydrogen at 535 C. anda pressure of 200 atmospheres. The beneficiated distillate will be foundto have a solvency in excess of its in- The nally beneficiated materialwill be 2,291,s15 i i termediate parent material and will be further.

characterized by an increment 'of low boiling fractions in excess offractional increment in the higher boiling range.

Inlthe step-wise action of hydrogen in the present invention, the firstaction of hydrogen'on the starting material is characterized byreduction of coke residue, specific gravity, vand viscosity in thestarting material. .In the first cycle of hydrogen action pressure aslow as 50 atmospheres are usable as are temperatures as low as 200 C.,however, higher temperatures and pressures are preferred, as` forinstance temperatures of 350-450 C. or thereabove and pressure o f inexcess of 200 atmospheres. Pressures and temperatures are, however, notrestricted to any definite limitations inasmuch as hydrogen treatmentthat reduces the coke residue, specific gravity and viscosity of thestarting material will proceed at lowered temperatures and pressures.Ihe desired temperatures and pressures are those that will reduce cokeresidue, specific gravity, and viscosity in a commercial manner. I Whenusing continuous operation in the first hydrogen cycle, flows ofl0,000-15,000 cubic feet per barrel feed stock have proven satisfactory,however,

higher and lower gas flows have proven effective.

In the last cycle of hydrogen action, as comprising a part of thepresent invention, for a given coordination of temperature and pressureas compared to the first cycle, the hydrogen flow in the last cycle isless than the flow in the first cycle. In the last cycle of hydrogenaction pressures as low as 50 atmospheres are usable as are temperaturesas low as 250 C. however, more elevated pressures and temperatures arepreferred, as for instance, pressures of in the order of 200 atmospheresand temperatures chosen from the range between 30D-750 C.

Aromatic tars of petroleum derivation or as produced from gas or gasesserve as suitable starting materials. Tars or fractions thereof, atleast once refined by hydrogen or other means also serve as startingmaterials.

Example 5.--It has been discovered that when subjecting certain mixturesof refined coal tar fractions to the action of hydrogen in accordancewith the present process for the production of solvents and/orplasticizers that the formerly accepted teaching that product increment,depolymerization and/or hydrogen absorption are linear functions of thetime, is not followed.

When subjecting a mixture of crude coal tar fractions boilingpredominantly above 250 C. or 275 C. to the action of hydrogen, researchhas disclosed that the newly induced products, depolymerization and/orhydrogen absorption are linear functions of the time. As ani'example,when-the above mixture of crude coal tar fractions is subjected to theaction of hydrogen for 2, 5, land 8-hour periods, the newly inducedproducts, depolymerization and/or hydrogen absorption were linearfunctions of the time element.

One of the preferred starting materials of the present process is amixture of refined coal tar fractions boiling predominantly above 355-or 380 C. Such a starting material is conveniently the final residueresulting from evaporating coal tar to dryness or substantial drynessand then stripping wood preservative from the distillate. This finalresidue mass of refined coal tar fractions is an especially suitablereiinedcoal tar pitch to be used as starting material of the presentprocess. However, in contradistinction to the mixture of crude coal tarfractions boiling predominantly above 250 or-300 C.,'whn the aforenamedpreferred starting material is subjected to the action of hydrogen forproduction of solvents and/or plasticizers, the newly induced fractions,depolymerization and/or hydrogen absorption are not, as described forthe other crude mixture of tar fractions, linear functions of the time.A critical period of treatment by or with hydrogen exists, and which ifexceeded causes loss of newly induced fractions, polymerization and/orlessened hydrogen absorption on certain fractions of the preferredstarting material under treatment.

The critical time element because of the obvious possible Variations inthe characteristics of the aforenamed rened coal tar pitch cannot bespoken of as an arbitrary figure.` It can be stated, however, that if'the refined coal tar pitch were to be subjected to the action ofhydrogen for such a length of time, which for other crude tar fractionswould illustrate that the newly induced fractions, depolymerizationand/or hydrogen absorption were linear functions of the time element,loss of induced products, polymerization and/or lessening of hydrogenabsorption would occur. When treating the rened coal tar pitch by orwith hydrogen, the vcritical time element is in the order of about threehours.

In the disclosures made herein and in the appended claimsdistillateremoval of low boiling portions from the beneciated material isconsidered the equivalent of fractional removal by sulfide partialpressure one and one quarter` atmospheres.. The beneciated material willbe found to have a lowered coke residue. specific gravity and viscosity.vand condensation of boiling points toward the lower end. 'Thebeneciated material is distilled to an upper limit of 340 C. with thedistillate serving as the intermediate startingmaterial. Theintermediate starting material is subjected to the action of hydro-` genat a temperature of 535 Cjand a pressure ofA 200 atmospheres. Thefinally beneciated material will be found to have a solvency in excessof its'intermediate parent materialand will be further characterized byan increment of low boiling fraction in excess of fractional incrementin the higher boiling range. By the higherboile ing range is meant, asan example. the upper half of the boiling range. fined coal tar pitch tothe action of hydrogen in accordance with the present process unless thetime period ofthe first hydrogen action is controlled at or below 'thecritical time, there will be experienced loss of 'fractionalincrementpolymerization and/or lessening of hydrogen'absorption. 'Ihe criticaltime element is in the order of about three hours and by the employmentof shorter' periods, fractional increment, depolymerization and/orhydrogen absorption follow the accepted teaching that they are linearWhen subjecting a re-v functions of the time element. By exceeding thecritical time element the converse is true.

By the term benecated as used herein 'and irrthe appended claims ismeant'the starting or intermediate starting material at least oncesubjected to the action of hydrogen in accordance to the presentprocess.

All sulfide catalysts effective in the presence of hydrogen are usable,as for instance those of the 6th and 8th periodic groups in any form orshape, as for example supported on carriers andpromoted or not; othercatalysts are usable therewith.

Other catalysts or materials influencing splitting or decomposition maybe used in conjunction with aforesaid sulfide catalysts.

In both cycles of hydrogen action, the present process is predicated onso controlling the reaction conditions that ring structures are notopened with the subsequent formation of liquid chain or parafnstructures to the extent that the solvents of enhanced solvency of thepres-` ent invention are impossible to manufacture.

vIn the cyclic action, process conditions are so controlled yas toinduce no' substantial percentage of carbonaceous increment. Whenutilizing most of the starting materials, the rst action of hydrogen ischaracterized by the depolymerization of high molecular complexes. Bythe term high molecular complexes is meant those high boilingfractions'especially susceptible to thermal degradation.

- In the second cycle of hydrogen action periods of asshort as oneminute at operating conditions have proven beneficial, however. longeror shorter periods may be used as for instance several minutes. As ageneral rule, it may be said that the time element in said second cycleis that pement in the higher boiling range;

rind necessary to provide final increment of low boiling fractions inexcess of fractional increandto induce solvency. f

The hydrogen supply used in the present process may come from anyconvenient source. as forI instance by the disassociation of methane. Ifdesired any diluting gas may be used in connection with the hydrogen. f

When the starting material has been subjected to the first rcycle vofhydrogen action that reduces coke residue, specific gravity and'viscosity; the stripping of the beneficiated mass may beeffected at anypoint desired as for "instance 200 C., or higher, or lower. Generallythe point of stripping is determined by the boiling Av'range .desired inthe product flowing -from the final action of hydrogen in the secondcycle. f

Within the limits of the boiling range of the finally beneciatedmaterial, solvents :and/or plasticizers may be fractionatedtherefrom; asfor instance to provide substitutes for the boilmg range or ranges ofanypf. the following:

The residue incidental to stripping action, or any residue incidental tosolvent or 'plasticizer recovery from the finally beneficiatedintermediate Astarting material may be recycled for fureration the cokeresidue inherent .to the starting ther product production. By suchrecyclingopf material can'be made to substantially ynally disappear..Startinamaterials include tars `and fractionsthereof, derived fromwood, coal', and petroleuml includinggases lof carbon content; as forinstance wood tar, pine tar, coke oven tar, gas

vhouse tar, water'gas'V tar and synthetic aromatic Atars derived frompetroleum sources vincluding gases containing carbon..

vStarting materials previously subjected to the Y the lower boilingrange in excessof fractional* action of hydrogen are suitable startinglmaterials. s In the disclosures herein made the removing .of low boilingfractions by gas movement or pressure release is considered theequivalent of distillation.

When reference is made to high molecular complexes contained in thestarting material, and when the starting material contains low boilingfractions that are not considered high molecular complexes, it isofcourse obvious that ythe high molecular complexes contained in thestarting material are to a certain extent depolymerized by the solventpresent.

A n especially attractive manner of practicing the present process is tofirst depolymerize the starting material with a solvent; as an example,

but not in a restrictive sense, a refractory solvent. Such use ofasolvent may be employed up to volume for volume, or more. After suchdepolymerization, the solvent and solute are then subjected to processvariables as noted in the foregoing. Such 'a procedure .is especiallyattractive when treating rened pitch.

Starting materials of the present process also include tars of aromaticcontentI from which low boiling fractions have been removed, as for.instance tars from which solvent oils have been removed, Viewedbroadly, the startingv materials ofthe presentprocessinclude tars ofaromatic content, fractions of said tar more viscous than the startingmaterial due to removal of low boiling fractions from the startingmaterial, high boilingfractions and pitches.

`The evaluation of solvent power is Aconven-l iently accomplished' byfinding thewell-known aniline point or Kauributanol number. a Theevaluation of plasticizing properties Iis conveniently accomplishedA byrecourse to methods suggested in Chapterv VI, the Technology of-Solvents" by Dr. Otto Jordon,y Mannheim, Germany,

newly induced fractions; vstripping newly induced fractions from thebeneflciated material; and subjecting at least la portion yof saidstripped fractions to the action of a relatively low iiow `of hydrogenat a. pressure of at least labout atmospheres and a temperature between465- .535 C. to provide. an increment of fractions in increment in thehigher boiling range.

2. In the production of a solvent from the refined pitch produced bystripping high temperature `coal tar to at least aboutsubstantialdryness, and fractionating the overhead material to recover'aliquid useful as a wood preservative, and a higher boiling fractionboiling predominantly above 355 C., the process which comprises:subjecting said higher boiling fraction tov the action of a. relativelyhigh now of hydrogen in the presence of hydrogen sulfide whilstcontacting a sulde catalyst for a period not in excess of labout threehoursy whereby\to avoid v loss of newly. induced fractions; strippingnewly induced fractions from the beneciated material;

and subjectingat least a portion of said stripped V fractions to theaction of a relatively low flow of hydrogen to provide an increment offractions in the lower boiling range .in excessof fractional prises:subjecting said higher boiling fraction to lthe action of a lrelativelyhigh iiow of hydrogen in the presence of hydrogen sulfide whilstcontacting a sulfide catalyst for a period not in excess of about threehours, 'whereby to avoid loss of newly induced fractions;l strippingnewly induced fractions from the bcneficiated material; and subjectingat least a portion of said stripped fractions to the action of arelatively low flow A of hydrogen to provide-an increment'of fractionstranslated by Ale`n D. Whitehead, Chemical Publishing Company* of NewYork, Incorporated,

New York, New York.

-Minor changes may be made within the scope of the appended. claimswithout departing from the spirit of the invention. In the claims amxedto this specification no selectionof any particuother modificationsthereof'.

., rclaim: I f

1. In the production of 'a solvent lfrom.the re- 'lar modication isintended to the `exclusion of fined pitch produced by stripping hightemperav ture coal tar to at least about substantialV` dryness, andfractionating the overhead material to recover a liquid useful as a.wood preservative,

and a higher boiling fraction boilingipredominantly abovel 355"a C., theprocess which comprises: subjecting said higher boiling fraction to theaction of a relatively high flow of hydrogen at a pressure in excessofabout'5 atmospheres and a temperature between about 35o-450 C. in

the presence of hydrogensulde whil'st`contactin the lower boiling rangein excess of fractional increment in the higher boiling range; andfractionating the last named beneiiciated material to provide asolventboiling preponderantly between '1009 C. and 150 C'. j 4. In theproduction of a solvent from the refined pitch produced by strippinghigh temperature coal tar to at least about substantial dryness, andfractionating theoverhead materialto recover aliquid useful as a. woodpreservative,` and a 4higher boiling fraction boiling predominantlyabove4 355 C., the process which com-v prises: subjecting saidhigherfboiling fraction to f the action of a relatively high ilow'ofhydrogen in the presence of hydrogen sulfide whilst con'-l tacting a'sulfide catalyst at a pressure in excess. of about 50 atmospheres and atemperature se-V lected between about S50-450 C. "for a period not inexcess of about three hoursp. whereby to avoid polymerization; strippingnewly induced fractions from the beneflciated material? andl subjectingat least a portion of said stripped fractions to the action of arelatively low flow ing a sulde catalyst for a period not in excess ofabout three hours, whereby to avoidlosswf of hydrogen at a pressure ofat least about 50 atmospheresand a vtemperature between .465- 535 C. toprovide an increment of fractions in the lower boiling range in excessof fractional-v duce a solvent,

5. In the production of a solvent from the refined pitch produced bystripping high temperature coal tar `to at least about substantialdryness, and fractionating the overhead material to recover a liquiduseful as a wood preservative, and ahgher boiling fraction boilingpredominently above 355 C., the/process which comprises: subjecting saidhigher boiling fraction to l0 the' action of a relatively high flow ofhydrogen in the presence of hydrogen sulde Whilst contacting a suldecatalyst at a temperature and pressure in excess of about 400 C. andabout 50 atmospheres, respectively, for a period not in excess of aboutthree hours, whereby to avoid lowered hydrogen absorption; strippingnewly induced fractions from the beneciated material; and subjecting' atleast a portion of said stripped fractions to the action of a relativelylow flow of hydrogen at a pressure of at least about 50 atmospheres anda temperature between 465-` v535 C. to provide an increment of fractionsin the lower boiling range in excess of fractional.

increment in the higher boiling range, to produce a solvent. c

JACQUELIN E. HARVEY, Jn.

